function f () {
  var a  = 1;
  let b = 2;
  {
    let  b =  3;
    var c = 4;
    let d = 5;
    debugger;
    console.log(a, b, c, d) //  1 3 4 5
  }
  {
    let b =  6;
    let d = 7;
    console.log(a, b, c, d)  //  1 6 4 7
  }
}
f()
